Photographic emulsions containing mercuric compounds having carbon-mercury bond



. tures above normal.

United States PHOTOGRAPHIC EMULSIONS CONTAINING MER- CURIC COMPOUNDS HAVING CARBON-MER- CURY BOND No Drawing. Application November 8, 1952, Serial No. 319,613

20 Claims. 01. 95-7 This invention relates to fog-inhibiting agents and stabilizers for photographic emulsions and to photographic emulsions containing them.

It is known that photographic emulsions, particularly ultra-sensitive emulsions or those containing optical sensitizers exhibit a tendency to form a deposit of silver in the emulsion upon development. This deposit extends more or less uniformly over the entire emulsion and is known as fog. Photographic fog is of two types: local and general. Local fog is formed by exposure of the film or plate at undesired points as by a light leak in the camera. General fog is formed in a number of ways. It may be caused by the conditions of high temperature or humidity or unusually long time of storage. The nature of the emulsion may also produce chemical fog as Well as the conditions of development of the emulsion as by development for protracted periods of time or at tempera- We are primarily concerned with fog and sensitivity changes in photographic films produced by storage under adverse conditions of temperature and humidity or for prolonged periods of time before exposure and development.

General fog and loss of sensitivity of the emulsion are especially likely to occur when the sensitive material is stored under conditions other than ideal, that is, under conditions of high temperature and humidity, as in tropical regions.

It is an object of the invention to provide novel antifogging or fog-inhibiting compounds for emulsions. A further object is to provide anti-fogging agents which stabilize the initial sensitivity of the emulsion. A still further object is to provide anti-fogging agents which improve the keeping of the emulsion in tropical regions. Other objects will appear from the following description of our invention.

These objects are accomplished by incorporating in a silver halide emulsion an organic compound of mercury which has a carbon to mercury bond. These compounds are organic compounds of mercury in which the mercury atom is attached by a non-ionic or covalent bond to an organic nucleus, especially a heterocyclic organic nucleus, and by an ionic or electrovalent bond to an anion.

The principal purpose of our invention is to provide a means for maintaining the sensitivity and fog of silver halide emulsions at or close to initial optimum values under keeping conditions of high temperature and humidity. The fog inhibitors which we propose to use are added to the emulsion at any stage during the process of manufacture prior to coating the emulsion to avoid loss of sensitivity and to inhibit the growth of incubation or keeping fog with passage of time under non-ideal conditions of storage. The mercury fog inhibitor may be added to the emulsion in solution in any convenient solvent not injurious to the emulsion such as water, lower alcohols and ketones.

A solution of the mercuric compound which we employ when added in suitable concentration before coating to unsensitized or optically sensitized silver halide emulsions atent O does not appreciably affect the sensitometric values for sensitivity and fog when measurements are made soon after coating. However, when sensitometric measurements are made after appreciable intervals of time under tropical or dry conditions of storage at elevated temperatures, these compounds do stabilize photographic speed and maintain fog at a low level.

The following compounds may be used according to our invention:

HgOl N/ 2-pyridy1 mercuric chloride N HgCOCHs 2-pyridy1 mercuric acetate HzNOHgOOCH;

(Ben, 35, 2038 (1902)) p-Aminophenyl mercuric acetate p-Hydroxyphenyl mercuric chloride 5. CH3

HgCl

NH- -HgOl (Schrauth and Bauerschmidt, Ben, 47, 2744 (1914) S-chloromercuri-l-chloromercuripheny1-4-methoxy-3-met yl- 3,4-dihydro-5-pyrazolone O 4! CH1 HgO -OH; 5

NH- HgOCOCH;

(Volkard, Ann., 267, 17s (1892) Steinkopf and Bauermeisterp Ann, 403, 59 (1914) 2,5-dichloromercurithiop one (Gilman and Wright, JACS, 55, 3302 (1933)) 2,5-dichloromereurifuran (Gilman and Wright, JACS, 55, 3302 (1933)) '2-chloromercurifuran (Volkai'd, Anrn, 267, 176 (1892) Steinkopf and Bauermeister, v

Ann, 403, 5 2-chloromercurithiophene (Travagli, Gazz. Chim. ItaL, 78, 592 (1948)) 2-amino-5-chloromercurithiazole ClHg HgCl (Sachs and Eberhartinger, Ben, 56, 2224 (1923)) 3,5-dichloromercuripyridine (Hurd and Wehrmeister, JACS, 7 1, 4009 (1949)) 2-acetamido-4,5-dichlo1-omercurithiazole C-NHC CH:

CHaO CH HOHzHgOC OCH 0 (Mills and Adams, JACS, 45, 1846 (1923)) 2-acetoxymercurimethyl-5-methoxy-2,3-dihydrobenzofuran (Ukai, J. Pharm. Soc. Japan, 47, 119 (1927)) S-chloromercuriquinoline (Hurd and Wilkinson, JACS, 70, 741 (1948)) 3,4-dichlo1'omercuri-2,5-dimethylfuran (Hurd and Wilkinson, JACS, 70, 740 (1948)) 3-chloromercuri-2,5-dimethylfuran HgC 1 L...

(Swaney, Skeeter-s, and Shreve,

Ind. and Eng. Chem, 32, 40)) 3-chloromercuripyridine The preparation of silver halide emulsions involves three separate operations: (1) the. emulsification and digestion or ripening of the silver halide, (2) the freeing of the emulsion from aqueous soluble salts usually by washing, (3) the second digestion or after-ripening to obtain increased sensitivity (Mees, The Theory of the Photographic Process, 1942, p. 3). The fog inhibiting agents may be added at any stage, e. g., after the final digestion.

The mercury compounds are useful generally in photographic silver halide developing out emulsions. They may be used in emulsions chemically sensitized with sulfur compounds, reducing agents or noble metals such as gold or by various combinations of these as described more fully hereinatfer.

The emulsions may be chemically sensitized by any of the accepted procedures; for example, they may be digested with naturally active gelatin, or sulfur compounds may be added such as those described in Sheppard U. S. Patents 1,574,944 and 1,623,499, and Sheppard and Brigham U. S. Patent 2,410,689.

The emulsions may also betreated with salts of the noble metals such as ruthenium, rhodium, palladium, iridium and platinum, all of which belong to group VIII of the periodic table of elements and have an atomic weight greater than 100. Representative compounds are ammonium chloropalladate, potassium chloroplatinate and sodium chloropalladite, which are used for sensitizing in amounts below that which produces any substantial fog inhibition, as described in Smith and Trivelli U. S. Patent 2,448,060, and as antifoggants in higher amounts, as described in Trivelli and Smith U. S. Patents 2,566,245 and 2,566,263.

The emulsions may also be chemically sensitized with gold salts as described in Waller and Dodd U. S. Patent 2,399,083, Damschroder U. S. Patent 2,597,856, and Yutzy and Leermakers U. S. Patent 2,597,915. Suitable compounds are potassium chloroaurite, potassium aurithiocyanate, potassium chloroaurate, auric trichloride and 2-aurosulfobenzothiazole methochloride.

The emulsions may also be chemically sensitized with reducing agents such as stannous salts (Carroll U. 3. Patent 2,487,850), polyamines such as diethylene triamine (Lowe and Jones U. S. Patent 2,518,698), polyamines such spermine (Lowe and Allen U. S. Patent 2,521,925), or bis-(,B-aminoethyl) sulfide and its watersoluble salts (Lowe and Jones U. S. Patent 2,521,926).

The most useful concentration of fog inhibitor is from about 0.05 to 1.0 mg. of fog inhibitor per mole of silver halide in the emulsion. Although higher amounts may be used we have found that no emulsion is likely to tolerate as much as 5 times this upper limit without serious desensitization.

The antifoggant and stabilizing action was determined by incubation of the emulsions for varying periods, usually about one week. The result of aging tests are tabulated below and compare speed, gamma and fog of the emulsions with and without the stabilizing compound. Speed was measured as 10/1, where i is the inertia.

Example 1 A medium speed gelatino-silver bromoiodide emulsion containing 0.24 mole of silver halide per liter was sensitized with a combination of potassium chloroaurate and a sulfur sensitizer such as disclosed in Sheppard U. S. Patent 1,574,944 and was then digested to optimum speed in the presence of a reduction sensitizer of the type disclosed in Carroll U. S. Patent 2,487,850. To a portion of this emulsion there was added 2-pyridyl mercuric chloride as shown in the following table. Each of these emulsions was coated and the coatings were exposed on a Ib Sensitometer and developed for three minutes in a developer of the following composition:

Grams N-m'ethyl-p-aminophenol sulfate 2.2 Hydroquinone 8.8 Sodium sulfite (desiccated) 96 Sodium carbonate, monohydrate 56 Potassium bromide 5 Water to 1 liter Upon holding the coatings for 1 week at 120 F. and 20% relative humidity, and testing both sets for speed, gamma cubation as in Example 1, the following results were obtained:

Fresh Test After Incubation Compound mg./mo1e Speed Gamma Fog Speed Gamma Fog 4 2 4 pyn y mercum chloride M 235 1.01 .00 270 1.22 .07

and fog, the following results were obtained: E l 4 A gelatino-silver bromoiodide emulsion was chemically sensitized with sulfur and gold sensitizers as in Example 1 and was then digested to optimum speed and divided into two portions and to one portion there was added 3-chl0romercuripyridine as shown in the following table. These portions were coated and exposed on a Ib Sensitometer A medium speed gelatino-silver bromoiodide emulsion was sensitized with 20 mgs. per mole of silver halide of allyl thiourea and 1.75 mgs. per mole of silver halide of potassium chloroaurate and digested for 20 minutes at 70 C. A poition of this emulsion was reduction sensitized by digesting for minutes at C. with 10 mgs. of triethylene tetramine per mole of silver halide. To portions of each of these emulsions there were added the mercuric compounds shown in the following table and the emulsions were coated on a cellulose acetate support, exposed on a Ib Sensitometer and developed for 3 minutes in a developer having the same composition as that used in Example 1. Upon incubation of each of the coatings as in Example 1 and testing both sets for speed, gamma and fog the following results were obtained:

Fresh Test After Incubation Compound mg./mole Speed Gamma Fog Speed Gamma Fog Cont! 7 320 0. 86 07 690 0. 71 13 (I) With methylene tetramine. 10 590 0. 86 10 440 0. 89 20 I+8-ehloromercuriquinoline- 0. 55 580 0.82 09 660 0. 74 13 Do 1. 10 630 0. 75 09 470 0. 80 10 I+2-ehloromercur1thiophene 0. 275 450 0. 91 10 520 0.82 18 D0 0.413 580 0.80 09 620 0. 76 l2 and developed for five minutes in a developer of the fol- Example 5 lowing composition:

. Grams N-methyl-p-aminophenolsulfate 2.5 Hydroquinone 2.5 Sodium sulfate (desiccated) 30 Sodium metaborate 10 Potassium bromide 0.5

Water to 1 liter Upon testing for speed, gamma and frog before and after incubation as in Example 1, the following results were obtained: Fresh Test After Incubation Compound Fresh Test After incubation Speed Gamma Fog Speed Gamma "Fog compound at Speed Gamma Fog Speed Gamma g Own- 1 420 0.70 .09 390 0. 50 .39 V Hg cu'npound 0.825 310 0.82 .09 390 0.64 14 Do 1.10 290 0.80 .08 220 0.77 .10 001mm 1,450 0.02 .05 1,200 0.82 .10 D0 1.38 240 0.96 .07 350 0.00 .10 3-chloromercuripyridine. 0. 90 1,400 0.52 .05 1, 350 0. 70 .08

Example 3 Example 6 A medium speed gelatino-silver bromoiodide emulsion A medium speed gelatino-silver bromoiodide emulsion was prepared and sensitized with a known sulfur sensitizer and was then digested to optimum speed and before coating, 600 mgs. of ammonium chloropalladate were added per mole of silver halide. The emulsion was divided into two portions and to one portion there was added 0.6 mg. of Z-pyridyl mercuric chloride per mole of silver halide. Portion-s were coated and exposed on a Ib Sensitometer and developed for four minutes in a developer of the same composition as that used in Example 1. Upon testing for speed, gamma and fog before and after inwas digested with 20 mg. per mole of silver halide of allylthiourea and divided into portions to which were added the mercury compounds shown in the following table. These portions were coated on cellulose acetate film support, exposed on a 117 Sensitometer, and developed for 4 minutes in a developer having the same composition as that used in Example 1. Upon testing for speed, gamma and fog before and after incubation for 4 weeks at 120 F., the following results were obtained:

Fresh Test After Incubation Compound rug/mole Speed Gamma Fog Speed Gamma Fog Control 255 1. 24 09 210 1. 09 50 s-Chloromercuriquinollue. 250 1. 19 08 185 1. 16 25 2-Chloromercurithiophene 240 1. 24 08 200 1. 12 32 .Do o. 250 1. 21 08 215 1. 14 28 Do 200 1. 27 08 210 1. 20 19 Instead of incorporation in the silver halide emulsion, the fog inhibitors of our invention may be incorporated in a colloid layer such as a gelatin layer on one or both sides of the support or they may be incorporated in a processing bath such as a developer or pre-bath.

The fog-inhibiting agents which we have described may be used in various kinds of photographic emulsions. In addition to being useful in ordinary non-sensitized emulsions they may also be used in orthochromatic, panchromatic and X-ray emulsions. If used with sensitizing dyes, they may be added to the emulsion before or after the dyes are added. Various silver salts may be used as the sensitive salt, such as silver bromide, silver iodide, silver chloride or mixed silver halides. The mercury compounds may be used in emulsions intended for color photography, for example, emulsions containing colorforming couplers, or emulsions to be developed by solutions containing couplers.

The dispersing agents may be gelatin or other colloid such as collodion, albumen, cellulose derivatives or synthetic resins.

It will be understood that we contemplate as included within our invention all modifications and equivalents falling within the scope of the appended claims.

We claim:

1. A light-sensitive silver halide emulsion containing a small amount of an organic compound of mercury in which the mercury atom is attached by a non-ionic mercury to carbon bond to a cyclic organic nucleus and by an ionic bond to an anion.

2. A light-sensitive silver halide emulsion containing a small amount of an organic compound of mercury in which the mercury atom is attached by a non-ionic mercury to carbon bond to a heterocyclic nucleus, and by an ionic bond to an anion.

3. A light-sensitive silver halide emulsion containing a small amount of an organic compound of mercury in which the mercury atom is attached by a non-ionic mercury to carbon bond to a pyridine nucleus, and by an ionic bond to chlorine.

4. A light-sensitive silver halide emulsion containing a small amount of an organic compound of mercury in which the mercury atom is attached by a non-ionic mercury to carbon bond to a pyrazolone nucleus, and by an ionic bond to an anion.

5. A light-sensitive silver halide emulsion containing a small amount of an organic compound of mercury in which the mercury atom is attached by a non-ionic mercury to carbon bond to a thiophene nucleus, and by an ionic bond to chlorine.

6. A light-sensitive silver halide emulsion containing a small amount of an organic compound of mercury in which the mercury atom is attached by a non-ionic mercury to carbon bond to a furan nucleus, and by an ionic bond' to chlorine.

7. A light-sensitive silver halide emulsion containing a small amount of a pyridyl mercuric salt.

8. A light-sensitive silver halide emulsion containing a small amount of a pyridyl mercuric halide.

9. A light-sensitive silver halide emulsion containing a small amount of 2-pyridyl mercuric chloride.

10. A light-sensitive silver halide emulsion containing a small amount of 3,5-dichloromercuri pyridine.

11. A light-sensitive silver halide emulsion containing a small amount of 8-chloromercuriquinoline.

12. A light-sensitive silver halide emulsion containing a small amount of Z-chloromercurithiophene.

13. A light-sensitive sulfur sensitized silver halide emulsion containing a small amount of an organic compound of mercury in whichthe mercury atom is attached by a non-ionic mercury to carbon bond to a cyclic organic nucleus and by an ionic bond to an anion.

14. The emulsion of claim 13 which is additionally chemically sensitized with gold salts.

15. The emulsion of claim 1 which is chemically sensitized with reduction sensitizers.

16. The emulsion of claim 13 which is additionally chemically sensitized with reduction sensitizers.

17. The emulsion of claim 13 which is additionally chemically sensitized with both gold salts and reduction sensitizers.

18. The emulsion of claim 13 in which the organic nucleus is pyridine and the anion is chlorine, and which is additionally chemically sensitized with both gold salts and reduction sensitizers.

19. The method of reducing fog and loss of speed upon storage of a silver halide emulsion, which comprises incorporating in said emulsion at any stage prior to coating, an organic compound of mercury in which the mercury-atom is attached by a non-ionic mercury to carbon bond to a cyclic organic nucleus and by an ionic bond to an anion.

20. The method of reducing fog and loss-of speed upon storage of a silver halide emulsion, which comprises incorporating in said emulsion at any stage prior to coating, a pyridyl mercuric halide.

References Cited in the file of this patent UNITED STATES PATENTS 1,738,530 Frankenburger et a1 Dec. 10, 1929 2,059,642 Kankelwitz Nov. 3, 1936 2,487,850 Carroll Nov. 15, 1949 2,540,086 Baldsiefen et al. Feb. 6, 1951 FOREIGN PATENTS 633,159 Great Britain Dec. 12, 1949 

1. A LIGHT-SENSITIVE SILVER HALIDE EMULSION CONTAINING A SMALL AMOUNT OF AN ORGANIC COMPOUND OF MERCURY IN WHICH THE MERCURY ATOM IS ATTACHED BY A NON-IONIC MERCURY TO CARBON BOND TO A CYCLIC ORGANIC NUCLEUS AND BY AN INOVIC BOND TO AN ANION. 